// Playground - noun: a place where people can play

import UIKit

var str = "Hello, playground"

// extension syntax
// computed properties
extension Double {
    var km: Double { return self * 1000.0 }
    var m: Double { return self }
    var cm: Double { return self / 100.0 }
    var mm: Double { return self / 1000.0 }
    var ft: Double { return self / 3.28084 }
}

let oneInch = 25.4.mm
let threeFeet = 3.ft

let aMarathon = 42.km + 195.m
println("A marathon is \(aMarathon) meters long")


// initializers
struct Size {
    var width = 0.0, height = 0.0
}

struct Point {
    var x = 0.0, y = 0.0
}

struct Rect {
    var origin = Point()
    var size = Size()
}

let defaultRect = Rect()
let memberwiseRect = Rect(origin: Point(x: 2.0, y: 2.0), size: Size(width: 5.0, height: 5.0))

extension Rect {
    init(center: Point, size: Size) {
        let originX = center.x - (size.width / 2)
        let originY = center.y - (size.height / 2)
        self.init(origin: Point(x: originX, y: originY), size: size)
    }
}

let centerRect = Rect(center: Point(x: 4.0, y: 4.0), size: Size(width: 3.0, height: 3.0))

extension Int {
    func repetitions(task: () -> ()) {
        for i in 0..<self {
            task()
        }
    }
}

3.repetitions({
    println("Hello")
})


extension Int {
    mutating func square() {
        self = self * self
    }
}

var someInt = 3
someInt.square()


// subscripts
extension Int {
    subscript(var digitIndex: Int) -> Int {
        var decimalBase = 1
        while digitIndex > 0 {
            decimalBase *= 10
            --digitIndex
        }
        return (self / decimalBase) % 10
    }
}

92835[8]

// nested types
extension Int {
    enum Kind {
        case Negative, Zero, Positive
    }
    var kind: Kind {
        switch self {
        case 0:
            return .Zero
        case let x where x > 0:
            return .Positive
        default:
            return .Negative
        }
    }
}

func printIntegerKinds(numbers: [Int]) {
    for number in numbers {
        switch number.kind {
        case .Negative:
            print("- ")
        case .Zero:
            print("0 ")
        case .Positive:
            print("+ ")
        }
    }
    print("\n")
}
printIntegerKinds([3, 19, -27, 0, -6, 07, 9])
